Semen Transport Made Simple For Mare Owners

Horse breeding has come full circle. In colonial times, mare owners waited for prominent stallions to come to their region. Fees were “per leap” or “to warrant,” the early-American equivalent of a live-foal guarantee.

Transportation advances in the 20th century reversed the situation. The mares did the traveling, while the valuable stallions stayed home.

Then, in 1981, the process reversed again — sort of. Now, the semen does the traveling. The mare owner signs a contract with the stallion owner, and the semen is delivered to the mare owner. The mare’s veterinarian inseminates her with the semen and 11 months later she has her foal.

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Sounds easy, doesn’t it' It can be. But it can also be a hair-pulling, shockingly expensive undertaking if things go wrong.

The Contract“Semen transport” refers to semen that has been recently collected and cooled to preserve viability for a short transit period, usually 24 to 48 hours. (Frozen semen is a different process.)

Start by asking the owner of the stallion you selected for a copy of the breeding contract. Study it thoroughly before committing your deposit. Most contracts require you to furnish a negative uterine culture and a vet’s statement attesting to the reproductive health of your mare. The contract may also dictate what immunizations your mare needs. The stallion owner goes through the expense of shipping semen, often repeatedly, and wants to be sure your mare can carry a foal.

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The contract should state “live-foal guarantee,” but be sure the term “live foal” is fully defined. A stallion owner may deem any foal that lives long enough to take two gasps of air as having satisfied the contract, while you might think the contract should be in effect until weaning. The most common definition of “live foal” is one that “stands and nurses,” which is the minimum you should accept.

Note what provisions are made if your mare fails to become pregnant or the stallion becomes unavailable or infertile. Also, pay close attention to the clauses concerning shipping containers and deposits. Some stallion owners tack on heavy fines for slow returns of containers.

It Takes TwoYour mare should be in peak health. Get a uterine culture done as soon as she begins cycling in the spring, so any infections found can be cleared up before you breed her.

It’s a big plus if the mare has obvious, regular heat periods and a tolerance for frequent rectal examinations. She will normally ovulate 24 to 48 hours before the end of a heat period, which usually lasts three to seven days. Ideally, your vet will inseminate the mare just prior to ovulation or, at the most, less than six hours after she ovulates.

Signs of this estrus or “heat” can fall anywhere on a spectrum from subtle to obvious (see sidebar). Mares in the “no doubt about it” category with heat cycles closer to seven days than three are beloved by stallion owners everywhere.

Tell the stallion manager as soon as your mare comes into estrus to allow him or her to plan the semen collection. Some farms only collect it on certain days of the week, while others also compete their stallions, so the stallion might not always be immediately available.

Next, call your veterinarian to determine when to start palpating your mare on a daily basis. Ovulation is tricky enough to predict when your mare is normal, but some some truly perverse mares will ovulate after they go out of heat.

Without knowing your mare’s idiosyncrasies, your vet will look for other hints during the rectal exams, such as whether her cervix is relaxed and the tone of her uterus.

As a rule of thumb, it’s better to inseminate too early and then request a second shipment a day later if the mare still hasn’t ovulated. If the semen arrives too late, you’re back to square one. Under ideal natural circumstances, sperm may live four days in a mare. but with semen transfer, its lifespan is shorter.

On The Collection EndThe true test of a stallion’s fertility via transported semen is the number of live foals produced each year by that stallion. Most breed registries will provide specifics on the number of mares the stallion bred by semen transport, as well as the number of subsequent foals registered.

Fertility depends upon both the stallion and the semen collector. When a stallion manager collects semen, he first filters out the gel fraction of the semen. He then examines the semen. Based on the number of healthy sperm in each ejaculate, he divides the collection into equal volumes, each containing enough semen to impregnate a mare. The industry standard is 1 to 1.5 billion motile sperm per insemination dose. This may seem outrageously high, but many sperm don’t survive the transport regimen.

After the semen is evaluated, it’s diluted with an extender of skim milk or cream-gelatin formula, which protects the semen from damage during transport and nourishes it until it’s placed in the mare. In addition, antibiotics are frequently added to the mixture to prevent the proliferation of bacteria. The semen is then placed in an appropriate container and shipped to the mare owner.

The VeterinarianYour veterinarian must be experienced in equine reproduction and dedicated, as semen transport is fraught with inconvenience. In addition, mares inevitably need inseminations on weekends and holidays.

During your veterinarian’s scheduled visits for rectal exams prior to ordering semen, double-check his supply of insemination equipment. As you know, semen is naturally meant to go directly from the stallion into the mare — anything else it contacts is potentially toxic. This includes light, air, some plastic insemination pipettes, soap, lubricant and especially the rubber stoppers found in some syringes. Anything marked “bacteriocidal” or “with preservatives” is also highly spermicidal.

ShippingMost stallion managers prefer to be notified early in the day if a shipment is needed, so schedule your veterinarian’s visits early enough to allow the stallion manager enough time to collect the semen and send it by overnight courier. Interestingly, we found most stud farms believe FedEx is the most reliable courier, based on sheer volume alone. Usually, the stallion manager makes the shipping arrangements.

Of course, other reliable overnight couriers do exist and may vary by area. If you live far from an airport and have a good rapport with your mail carrier, you could try Express Mail. If the distance between your mare and the stallion is less than 500 miles, consider ground transportation, such as by bus, and don’t overlook the possibility of picking up the semen yourself.

InseminationWhen the semen container arrives, don’t open it. Contact your vet and get the mare ready. Wrap her tail in a sterile gauze wrap, or, if she’s quiet, secure a plastic examination sleeve over the whole tail. Scrub her perineal area with an antiseptic soap, including 10 inches of her hindquarters in both directions. Rinse the area thoroughly and air dry or dry with paper towels. Remember, soap residue and plain water are both spermicidal.

At this point, the vet will open the container to verify the semen is from the right stallion and ascertain the volume of extended semen shipped. Do not, under any circumstance, warm the semen. This is probably the No. 1 mistake made by rookies.

The vet will gently invert or rotate the packet of semen to mix the contents and draw out the required amount of semen for insemination into a non-toxic syringe slightly wa rmer than the semen itself. (AIR-TITE syringes are recommended. 800/231-7762.) For an average mare, the amount infused will be between 40 and 60 ccs.

The package should include the amount of semen to be infused, extender used, name of the stallion, percentage of pre-shipping motility, and which, if any, antibiotic was used with the extender. Once the semen is drawn up, the syringes must be protected from light and used as quickly as possible. Your veterinarian will don a sterile glove and insert the pipette through your mare’s relaxed cervix and infuse the semen.

Some registries may require the veterinarian to sign a statement verifying the semen was used only on your mare. He may also choose to repack the remaining semen and take it back to his office to estimate the post-shipping motility. He will probably arrange to return the next day to confirm ovulation. If your mare has not ovulated as expected, order another shipment of semen for the following day.

Bottom LineIf you’ve followed our instructions — and the mare, stallion, stallion manager, veterinarian and delivery service all cooperated — congratulations are in order. You’ve survived your first semen-transport experience. There’s nothing left to do but cross your fingers for the next two weeks until your veterinarian returns to check for a pregnancy. Don’t be discouraged if your mare fails to get in foal on the first try. With good management and attention to detail, semen transport has the same live-foal rate as natural-cover breeding.